About our research

Our research spans the globe and attempts to combine laboratory based manipulations with global datasets to help define geochemical cycles. We loosely define our work into three categories global, local, and extreme. Our global scale research involves a modeling intensive approach to describing global biogeochemical cycles. Meanwhile local implies regional or smaller scale work, which largely concentrates on the microbial ecology of salt marsh and freshwater wetland ecosystems. In extreme environments we primarily explore individual site(s) that typify some characteristic condition (e.g. hydrothermal sediments for high temperatures and brines for salty environments). 

Global

The evolution of global datasets derived from remote sensing techniques and the great expansion of existing datasets have allowed us to generate highly interconnected biogeochemical models. Our lab is focusing on scouring numerous databases with valuable geochemical data and collating these data to help inform current models, refine our understanding of geochemical cycles, or explore new hypotheses. This work is perhaps some of the most interdisciplinary in our lab, which includes geographical, geological, biological, and chemical techniques. On a given day a researcher can switch between the haversine formula and microbial kinetics. Previous work in this research arm has involved describing the sulfur cycle in marine sediments. Currently we are investigating the global nitrogen cycle and are particularly interested in the emission of nitrous oxide.

Relevant Publications

Kölling, M., Bouimetarhan, I., Bowles, M.W., Felis, T., Goldhammer, T., Hinrichs, K.-U., Schulz, M., Zabel, M. (2019) Quaternary sea-level changes modulate atmospheric CO2 and O2 via pyrite weathering. Nature Geosciences, 1-6, https://doi.org/10.1038/s41561-019-0465-9

Wörmer, L.P., Hoshino, T., Bowles, M.W., Viehweger, B., Adhikari, R.R., Xiao, N., Uramoto, G., Könneke, M., Lazar, C.S., Morono, Y., Inagaki, F., Hinrichs, K.-U. (2019). Microbial dormancy in the marine subsurface:global endospore abundance and response to burial. Science Advances, 5(2): eaav1024.

Bowles, M.W., Mogollón, J.M., Kasten, S., Zabel, M., Hinrichs, K.-U. (2014) Global rates of marine sulfate reduction rates and implications for subseafloor metabolic activities. Science 344(6186): 889-891, doi: 10.1126/science.1249213

Local

Southeastern Louisiana is a unique environment defined by significant impacts from human perturbations. The acute (e.g. oil spills) and chronic effects (e.g. climate change) of human activity are exacerbated in this region given its proximity to the ocean and low sea-level. We are currently pursuing fundamental questions regarding the microbial ecology of salt marsh and wetland regions to acquire baseline knowledge of this rapidly evolving environment. A major component of this research involves describing how environmental change will ultimately influence microbial processes. As we define this change a significant part of this work will involve means of upscaling these impacts to beyond our ecosystem.

Relevant publications

Meador, T.B., Bowles, M.W., Lazar, C.S., Zhu, C., Teske, A., Hinrichs, K.-U., (2015) The archaeal lipidome in estuarine sediment dominated by members of the Miscellaneous Crenarchaeotal Group. Environmental Microbiology 17(7): 2441-2458, doi:10.1111/1462-2920.12716

Extreme

Extreme environments are a relative term here for a lack of better description. What humans consider extreme most microbes could care less about! The applications of this work are incredibly interesting in that they can perhaps shed light on the origins of life, ancient geochemical cycles, and help to constrain where life in our solar system and abroad may exist. Previous work on this topic has involved exploring cold seeps, hydrothermal sediments, and Antarctic lakes. Future work will focus on microbial ecology of cold seep environments, Arctic ice cores, and the deep subsurface.

Relevant Publications

Bowles, M.W., Samarkin, V.A., Hunter, K.S., Finke, N., Teske, A.P., Girguis, P.R., Joye, S.B. (2019) Remarkable capacity for anaerobic oxidation of methane at high methane concentration. Geophysical Research Letters, https://doi.org/10.1029/2019GL084375 

Schutte, C.A., Samarkin, V.A., Peters, B., Madigan, M.T., Bowles., M.W.,Morgan-Kiss, R., Casciotti, K.,Joye, S.B.(2019).Vertical stratification and stability of biogeochemical processes in the deep saline waters of Lake Vanda, Antarctica. Limnology and Oceanography,  https://doi.org/10.1002/lno.11327

Bowles, M.W., Hunter, K.S., Samarkin, V.A., Joye, S.B. (2016) Variations in geochemical signatures and microbial activity within and between diverse cold seep habitats along the lower continental slope of the Gulf of Mexico. Deep Sea Research II.  Topical  Studies in Oceanography 129, 31-40.

 Crespo-Medina, M., Bowles, M.W., Samarkin, V.A., Hunter, K.S., Joye, S.B. (2016) Microbial diversity and activity in seafloor brine lake sediments (Alaminos Canyon 601, Gulf of Mexico). Geobiology 14(5), 483-498.

 Saxton, M.A., Samarkin, V.A., Schutte, C.A., Bowles, M.W., Madigan, M.T., Cadieux, S.B., Pratt, L.M., Joye, S.B. (2016). Biogeochemical and metagenomic evidence supports a novel mode of anaerobic methanotrophy in permanently ice-covered Lake Fryxell, Antarctica. Limnology and Oceanography 61(S1).

Inagaki, F., Hinrichs, K.-U., Kubo, Y., Bowles, M.W., et al. (2015) Exploring deep microbial life in coal-bearing sediment down to ~2.5 km below the ocean floor. Science 349 (6246): 420-424, doi: 10.1126/science.aaa6882